Reproduction of the Cape Horned Lizard, Phrynosoma coronatum (Squamata: Phrynosomatidae) from Baja California Sur, Mexico

2011·1.6 MB·English

by  Stephen R Goldberg

1
Bull. SouthernCaliforniaAcad. Sci.
110(2).2011.pp.56-58
©SouthernCaliforniaAcademyofSciences,201
Reproduction ofthe Gape Homed Lizard, Phrynosoma
coronatum (Squamata: Phrynosomatidae) from Baja California
Sur, Mexico
Stephen R. Goldberg
Whittier College, 13406 E. Philadelphia St. Whittier, CA 90608,
[email protected]
Species ofPhrynosoma (formerly P. coronatum) range west ofthe Sierra Nevada from
Shasta County, California, south through southern California and Baja California
(Grismer2002). Montanucci (2004) and Leacheetal. (2009)consideredPhrynosomafrom
the southern tip of Baja California as P. coronatum. Goldberg (1983) reported on
reproduction in Phrynosoma blainvillii (as P. coronatum) from southern California. To
my knowledge, there is no information on reproduction ofP. coronatum from the Cape
Region ofBaja Cahfornia Sur, Mexico. Thepurpose ofthis noteisto reporttheresultsof
a histological examination of P. coronatum gonads from the Cape Region of Baja
California Sur to ascertain whether geographic variation in reproduction exists between
northern and southern species ofPhrynosoma (formerly P. coronatum, sensu Montanucci
2004, Leache et al. 2009).
A sample of fourteen P. coronatum consisting of seven adult males (mean SVL =
76.9 mm ± 9.1 SD, range: 61-90 mm), five females (mean SVL = 79.2 mm ± 14.0 SD,
range: 67-103 mm), one presumed neonate (SVL = 27 mm) and one presumed young of
the year (SVL = 36 mm) was examined from the herpetology collection ofthe Natural
History Museum of Los Angeles County (LACM), Los Angeles, California, U.S.A.
(Appendix). Phrynosoma coronatum were collected 1964, 1967 and 1968.
For histological examination, the left testiswas removed frommales and theleft ovary
mm
was removed from females. Enlarged follicles (> 5 length) were counted. Tissues
were embedded in paraffin and cut into sections of5 |im. Slides were stained with Harris
hematoxylin followed by eosin counterstain (Presnell and Schreibman 1997). Slides of
testes were examined to determine the stage ofthe spermatogenic cycle. Slides ofovaries
were examined for the presence of yolk deposition. An unpaired /-test was utilized to
compare P. coronatum male and female mean body sizes (SVL) using Instat (vers. 3.0b,
Graphpad Software, San Diego, CA). Histology slides were deposited in LACM.
There was no significant size difference (mean SVL) between males and females ofP.
coronatum (unpaired t test, / = 0.35, df = 10, P = 0.73). The only stage present in the
testicular cycle was spermiogenesis (sperm formation) in which the lumina of the
seminiferous tubules were lined by clusters ofsperm and/or metamorphosing spermatids.
This condition was noted in the followingmonthly samples: (July, n = \; August, n = 6).
The testes were previously removed leavingtheepididymidesin oneAugustmale (LACM
109380). Tubules ofthe epididymis were filled with sperm so it was assumed the missing
seminiferous tubules were undergoing spermiogenesis. The smallest spermiogenic male
(LACM 19904) measured 61 mm SVL and was from August.
Monthly stages in the ovarian cycle are in Table 1. Three stages were noted: (1)
quiescent, no yolk deposition; (2) early yolk deposition, basophilic yolk granules in the
ooplasm: (3) enlarged ovarian follicles > 5 mm. One female from July (LACM 101500)
56
PHRYNOSOMA CORONATUMREPRODUCTION IN BAJA CALIFORNIA SUR 57
Table 1. Monthly stages in the ovarian cycle offive P. coronatum frorr1 Baja California Sur, Mexico.
Month n Quiescent Earlyyolk deposition Enlarged follicles > 5 mm
July 2 1 1
August 2 1 1
October 1 1
contained 12 enlarged follicles (> 5 mm) that would have ovulated later in the summer.
This is within the range of7-16 clutch sizes reported by Goldberg (1983) for P. blainvilli
(as P. coronatum) females from southern California. This was also the smallest
reproductively active female (SVL = 71 mm). One female from August (LACM 19907)
exhibited early yolk deposition which would have resulted in an egg clutch being
produced during the coming autumn.
One presumably neonate (LACM 101504, SVL = 27 mm) was collected 17 July and
onejuvenile (LACM 19905, SVL = 36 mm) was collected 9 August both indicating P.
coronatum commenced reproduction earlier in the year.
My data indicate a significantly longer reproductive cycle for P. coronatum from the
Cape Region ofBaja California Sur as compared to P. blainvillii in southern California
(Goldberg 1983). Insouthern CaliforniaP. blainvillii(formerlyP. coronatum) isa "spring
breeder" inwhichreproductiveactivitycommencesin March andends byJuly(Goldberg
1983). In the Cape Region of Baja California Sur, reproduction ofP. coronatum occurs
through summer. Also, the appearance of a presumed neonate in July and a larger
presumed young of the year in August suggest that P. coronatum commenced
reproduction earlier in spring, perhaps concurrent with northern species ofPhrynosoma
(sensu Montanucci 2004, Leache et al. 2009). Furthermore, winter activity has been
reported for P. coronatum in the Cape Region (Vandenburgh 1895, Leviton and Banta
(1964). In view of the extended reproductive season in the Cape Region, it appears
femalesofP. coronatummayroutinelyproducetwoclutchesperseason, although thishas
yetto be observed. Goldberg (1983) indicated two clutches might be possible for some P.
blainvillii(asP. coronatum) femalesfrom southernCalifornia. In contrast, Howard (1974)
reported one clutch was produced by Phrynosoma from northern Baja California.
Acknowledgements
I thank Christine Thacker (LACM) for permission to examine P. coronatum.
Literature Cited
Goldberg, S.R. 1983. Reproduction of the coast horned lizard, Phrynosoma coronatum, in southern
California. Southwestern Naturalist, 28:478-479.
Grismer, L.L. 2002. Amphibians and Reptiles of Baja California including its Pacific Islands and the
islands in the Sea ofCortes. University ofCalifornia Press, Berkeley, xiii + 399 pp.
Hovv'ard, W.R. 1974. Comparative reproductive ecology of horned lizards (Genus Phrynosoma) in
southwestern United States and northern Mexico. Journal ofthe ArizonaAcademy ofScience, 9:
108-116.
Leache,A.D.,M.S.Koo,C.L.Spencer,T.J.Papenfuss,R.N.Fisher,andJ.A. McGuire.2009.Quantifying
ecological,morphological,andgeneticvariationtodelimitspeciesinthecoasthornedlizardspecies
complex {Phrynosoma). Proceedings ofthe National Academy ofSciences, 106:12418-12423.
Leviton,A.E.andB.H. Banta. 1964. MidwinterreconnaissanceoftheherpetofaunaoftheCapeRegionof
BajaCalifornia,Mexico.ProceedingsoftheCaliforniaAcademyofScience,4"'series,330:127-156.
58 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES
Montanucci, R.R. 2004. Geographic variation in Phrynosoma coronatum (Lacertilia, Phrynosomatidae):
further evidence for a peninsular archipelago. Herpetologica, 60:117-139.
Presnell, J.K. and M.P. Schreibman. 1997. Humason's Animal Tissue Techniques. The Johns Hopkins
University Press, Baltimore. 572 pp.
Vanderburgh, J. 1895. Review of the herpetology of Lower California. Proceedings of the California
Academy ofScience, 2:77-163.
Appendix
Phrynosoma coronatum from the Cape Region ofBaja California Sur examined from
the herpetology collection of the Natural History Museum of Los Angeles County
(LACM), LosAngeles, California U.S.A. (LACM 19903, 15 km E San Bartolo), (LACM
19904, 19905, 19906, vie. Santiago), (LACM 19907, 38 kmNW LaPaz), (LACM 101500,
101502, 101503, 101504, 101506, 109378, 109379, 109380, 109381, La Paz).